Process for varnishing sliding clasp fasteners



Patented Mar. 21, 1939 raocass FOR VARNISHING sLmmo CLASP FASTENERS Carl Miiueler, Wuppertal-Barmen, Germany No Drawing. Application February 3, 1936, Se-

rial No. 62,226.

3 Claims.

This invention relates to a process for varnishing sliding clasp fasteners. It has been often proposed to varnish sliding clasp fasteners to make them suit the color of the garment to be equipped with the sliding clasp fastener or to give them for any other reason a better appearance than the color of the metal permits of which they are made. A varnish coating makes it possible to employ for the manufacturing of the fastener elements cheaper, more easily oxidising metals.

Up to the present it has not been possible to perfectly varnish a sliding clasp fastener. The reason herefore is that the varnish coating of the fastener elements must be able to meet extraordinarily high requirements as regards fastness, as these elements are very strongly rubbed during the closing and opening of the slidingclasp fastener and when the elements are bent when being clamped on the carrying band. Even the experiments to obtain a favorable result by employing special varnishes have not been successful as the greatest difliculty consists in the application of the varnish coating onto the fastener elements.

According to the invention a result, never attained up to the present, is obtained in that on the cleaned fastener elements a thinnest possible coating of varnish is applied, the elements are then not completely dried and this process is repeated several times, preferably ten times or 30 more. The laying on of the varnish can be done before the fastener elements are fixed on the carrying band and preferably in a rotary drum by spraying. Prior to every fresh application of varnish the slightly dried, baking together fastener elements are preferably separated by tossing, centrifuging or by any other suitable treatment. The fastener elements are completely dried after the last application of varnish. When proceeding in this manner it is advisable to heat the varnished fastener elements before clamping them on the carrying band, to prevent the coating from cracking. Or-the fastener elements are slightly dried after the application of the last coating of varnish, clamped on the carrying band and only then completely dried.

The production of a varnished sliding clasp fastener can be carried out for example as follows:--

Steep the fastener elements in acid, for instance diluted hydrochloric acid to be cleaned of dirt and roughened. Remove any traces of acid by washing in water and in benzol. Charge the fastener elements in an irregular heap into a rotary drum, about 20 kg. if the rotary drum and the fastener elements are of normal size.

In Germany February 8, 1935 Spray up to '70 grams of varnish onto the fastener elements at room temperature, the drum being continually rotated, so that a film-thin varnish coating is produced on every single fastener element. As varnish any oil varnish capable to dry in an oven or any special varnish may be used. Dry the varnished fastener elements in an oven at 100 to 110 C. during 1 to 2 hours. Bring the clump of fastener elements sticking together into a tumbling box, which is about 2 meters high and has an inclined bottom leading to a collecting chamber, and actuate this box to separate the elements. Instead of a tumbling box a centrifuging apparatus or any other suitable separating device may be used. Varnish again the fastener elements as described above, slightly dry the same, separate the fastener elements and repeat these treatments according to the kind of varnish about times until the fastener elements have a coating of suificient thickness.

After the last coating with varnish the fastener elements are dried at 140 to 170 C. during 3 to 8 hours, according to the kind of varnish and color so that the coating is completely hardened. Black or brown varnishes require stronger heating, whereas green, yellow, white and red varnishes are dried at the lower temperatures indicated above, as they are sensitive against strong heating. The finally varnished elements are heated again to about 90 before they are pressed on to the carrying band so that cracking or peeling off of the varnish coating is prevented with certainty. After the last application of varnish the fastener elements may at first be dried only at about 110 to- 115 C., then fixed on the carrying band at room temperature and finally completely dried at about 140 C. during 4 to 6 hours.

In this manner it is possible to provide on fastener elements of sliding clasp fasteners varnish coating resistant against pressure and scouring. This varnish coating fulfills all requirements. For the clasp of the sliding clasp fastener a varnish coating as usual for other small metal articles is sufficient, the interior of the clasp being, however, shut off to prevent penetration of var- .nish, as rubbing of varnished surfacesthe one on the other is less favorable for the duration of a sliding clasp fastener than rubbing of metal on varnish. If the varnish is applied by spraying a thin plate inserted between the jaws of the clasp and having a wedge-shaped aperture for the heart-shaped piece of the sliding clasp is sufficient for covering the interior of the clasp.

The invention is evidently not limited to the above described examples, as many alterations and other forms of carrying out the process are possible. The temperatures indicated. the number of consecutive applications of varnish may be selected in accordance with the kind of varnish which is employed. The varnish may be applied on the fastener elements instead of by spraying by slow pouring on or dripping on or in that varnish is charged in the drum and the fastener elements are coated with varnish when the drum is, rotating.

I claim:-

I. The process of varnishing elements of separable fasteners, comprising pickling the elements, tumbling them, applying a very thin film of varnish to the elements while tumbling them, heating the elements to partly dry their films so that they are still soft, mechanically separating the elements, repeating the tumbling, varnishing, and drying operations until the coat of superimposed films of varnish on the elements has attained the desired thickness, completely drying the elements and securing them on the carrying band.

2. The process of varnishing elements 01 separable fasteners, comprising pickling the elements, tumbling them, applying a very thin film of varnish to the elements while tumbling them, heating the elements to partly dry their films so that they are still soft, mechanically separating the elements, repeating the tumbling, varnishing, and drying operations until the coat of superimposed films of varnish on the elements has attained the desired thickness, then completely drying and cooling the elements and then reheating them and securing them on the carrying band.

3. The process of varnishing elements of separable fasteners, comprising pickling the elements, tumbling them, applying a very thin film of varnish to the elements while tumbling them, heating the elements to partly dry their films so that they are still soft, mechanically separating the elements, repeating the tumbling, varnishing, and drying operations until'the coat of superimposed films of varnish on the elements has attained the desired thickness, then fixing the elements on the carrying band and finally completely drying the elements.

CARL MAUELER. 

